The invention involves a cutting tool for the deburring of bores and placing of chamfers at both ends of through bores with at least one cutting blade, consisting of a rectangular-edged cutting blade having tapering cutting edges which remove material from the bore. The cutting edges contain undercut, sharpened free spaces and the cutting blade has a bearing surface on its front end for setting inside the through hole.
Such cutting blades are known from the applicant's U.S. Pat. No. 4,140,432, the underlying problem of which is to precisely position a chamfer with an exactly defined size on both sides of the through hole.
Such cutting blades of this type, for removing burrs of through holes or placing of chamfers, are preferably used in pairs. In this case the cutting blades are installed in a rectangular reception slot in a rotary tool holder so as to face in opposite directions with radially, outward tilted, conical cutting edges.
The cutting blades are urged outwards via pins on a shaft by a spring inside the tool holder. The pins each engage a slot on the cutting blades.
The cutting blades are thus moveable radially in the same direction. In a resting, inoperative position the cutting blades are urged radially outward under spring tension. When operating to debur or chamfer the edges of a through hole, the cutting blades are progressively displaced radially inward against the spring tension until they finally reach the inside of the through hole in a non-cutting position within the tool holder. This is caused by the feed of the tool holder and the conical shape of the cutting edges which acts to progressively urge the blades inwards as the tool holder is fed into the bore.
The tool holder with the cutting blades is then driven through the through hole in order to work on the rear edge of the through hole with the feed working in reverse.
The cutting blades also have an additional cutting edge at the opposite end, so that the edge of the through hole can be deburred and chamfered from the rear also, after the through hole has been driven through and with the same cutting procedure but in the reverse feed direction.
However, it has not been possible to place chamfers very precisely with existing deburring and cutting tools, particularly in soft materials.